A double ridged horn antenna with trapezoidal grooves is proposed in this paper. The trapezoidal groove structure is introduced into the aperture plane and the outer side wall, which can effectively suppress the current on the outer wall of the horn, so as to reduce the sidelobe of the horn antenna. The horn wall of antenna is designed as hollow structure, which reduces the weight of antenna. The antenna adopts the 3D printing technology, which effectively solves the problems of difficult processing and poor consistency in traditional methods. The simulated and measured results show that the proposed antenna design can effectively improve the antenna gain. The antenna gain is higher than 10.32 dBi and the return loss is lower than -10 dB at the operating frequency band of 5~ 10 GHz and the peak gain reaches 14.61 dBi at 9.6 GHz. Adopting the hollow structure design of the antenna wall can reduce the antenna mass by 74%. The test results are basically consistent with the simulation ones.